Electrodeposition of tin-nickel alloy



Patented Nov. 10, 1953 Norman Parkinson, Hayes, England, assignor to John Ireland, Middlesex, England No Drawing. Application May 9, 1950, Serial No. 161,017

Claims priority, application Great Britain November 22, 1949 1 Claim.

This invention relates to the electrodeposition of tin-nickel alloy.

The electrodeposition of tin and nickel separately is well known as is also the principle of using small quantities of a second metallic ion to improve the smoothness of the deposit of the primary metal. Thus one particular proposal that has been made is to use from 2 to g./l. of a nickel salt to improve the tin coating deposited from a bath containing stannous chloride and alkali fluoride but to obtain satisfactory deposits from this bath it is essential that it contains one or more of the organic addition agents used in the electro-plating industry for improving the smoothness of deposits.

According to the present invention I electrodeposit tin-nickel alloy coatings containing not more than 90% nor less than 50% of tin from an aqueous solution of appropriate salts of tin and nickel containing the respective. metals in proportions between 2:1 and 1:7.

The electrolyte must contain tin and nickel cations and may contain the cations of an alkali metal including ammonium. The anions may be chlorides alone, or chlorides and fluorides, or chlorides sulphates and fluorides, or fluorides alone.

An important feature of the baths used in accordance with the present invention is that they produce satisfactory smooth deposits in the absence of organic addition agents.

The tin and nickel cations may be replenished by using anodes of an appropriate tin-nickel alloy. Alternatively separate tin anodes and nickel anodes may be used. In the latter case replenishment may be effected either by passing the total current through each anode successively for an appropriate time or by using the tin and nickel anodes simultaneously and apportioning the current through them appropriately.

For some purposes it may be convenient to use either tin anodes or nickel anodes and to supply the other metallic cation by adding to the bath suitable salts,

Further features of the invention will be apparent from the examples given hereafter of baths that I have found to give satisfactory results at the temperature and with the current density shown. Approximate composition of the allow coating obtained is also shown.

2 Example I G./l. SnCl-z, 2Hz0 100 5 NiClz, 6H2O 400 NaF 55 NH4HF2 70 Temperature 65 C., 27 amps/sq. ft. Coating Sn m 55%, Ni 45%.

Example II G./l. SnClz, 2H2O 100 NiF2 75 16 NiCl2, fiHzO 325 K01 100 Temperature 65 C., 20 amps/sq. ft. Coating Sn 20 Example III G./l. SnF2 NaF '75 25 NiC12, 6H2O 200 Temperature 65 C., 27 amps/sq. ft. Coating Sn Example IV G./l. SnClz, 2H2O NaF 30 NH4HF2 30 NiClz, 6H2O 35 Temperature 0., 24 amps/sq. ft. Coating Sn Example V G./l. 40 SnClz(anhydrous) 20 NiC12,6H2O 300 Temperature 65 0., 10 amps/sq. ft. Coating Sn It is to be understood, however, that the foregoing examples are given purely by way of illustration to describe the nature of the invention and not to limit its scope, and we may vary the actual ingredients of the baths and the proportions of such ingredients as also the operating temperature and current density depending upon 3 any practical requirements that may have to be References Cited in the file of this patent fulfilled.

I claim: UNITED STATES PATENTS A process which comprises electrodepositing Number Name Date on-nickel a11oy coatin s from an aqueous solu- 5 Re11624 Alexander 3, 1897 men bath con tltuted as foll ws. G A 1404156 Maxim Jan 17, 1922 2,085,543 Oplinger June 29, 1937 2H2) 2,119,304 Viers et a1 May 31, 1938 Nlch 3 10 2,183,384 Viers et a1 Dec. 12, 1939 NEF 55 2,381,778 Schoonmaker et a1. Aug. '7, 1945 NH4HF2 '70 NOR.MA N PARKINSON. 

